4. Functions

Activity 4.1: Creating a Calculator

Solution

1. Create a new file within the Chapter04 directory with the name activity.php.
2. Start your script with the opening PHP tag and set the strict type to 1:

   <?php
   declare(strict_types=1);

3. Now we can start by writing our factorial function in the same file:

   activity.php

   13 function factorial(int $number): float
   14 {
   15     $factorial = $number;
   16     while ($number > 2) {
   17         $number--;
   18         $factorial *= $number;
   19     }
   20     return $factorial;
   21 }

   https://packt.live/31nkK8E

   Let me explain what the function does. First of all, it takes an integer argument; we can be sure that it will always be an integer because we added a type hint and declared that we are using strict types. There are several...